Position rack in center of oven and heat to 350 degrees. Butter and flour a standard loaf pan (9 x 5). In a large bowl, combine the flour, sugar, baking powder, and salt. Whisk until well blended. Stir in the cranberries and or blueberries. In a medium bowl, combine the buttermilk, eggs, vanilla, and orange zest. Whisk until blended. Pour the wet ingredients over the dry ingredients. Add the melted butter. Using a silicone spatula, gently fold until blended. Scrape the batter into the prepared pan and spread evenly. Bake on a sheet pan, rotating halfway through, until the top is golden and a wooden skewer or toothpick inserted in the center comes out clean, *50 to 55 minutes. Let cool in the pan on a rack for 30 minutes. Invert the bread and remove from pan, turn the bread right side up , and let cool completely. In a small bowl, stir the confectioners' sugar and the orange juice until smooth, add more juice, 1 tsp. at a time until the glaze is just pourable. Drizzle the bread with the glaze and let sit for 30 minutes before serving. *NOTE: When making mini loaves the baking time is reduced to 33 minutes. Also use disposable pans and leave the glazed bread in the pans. That way they can be given away easily.